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swapnadeep.ganguly
Active User
Joined: 21 Mar 2007
Posts: 203
Location: India
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Hi,
In the FD part, we specify the word BLOCK CONTAINS XX RECORDS.
Can anyone please let me know what actually this means.
Basically I have to read from a table into a flat file. The table has a max of 200 entries. So shall I Mention
BLOCK CONTAINS 200 RECORDS??? |
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murmohk1
Senior Member
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Joined: 29 Jun 2006
Posts: 1436
Location: Bangalore,India
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Swapna,
Let the block size determine at run time. |
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swapnadeep.ganguly
Active User
Joined: 21 Mar 2007
Posts: 203
Location: India
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| So, I am required not to specify anything at COBOL as well as the JCL?? |
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acevedo
Active User
Joined: 11 May 2005
Posts: 344
Location: Spain
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nope, not specified is not the same as specify 0.
code
| Code: |
| BLOCK CONTAINS 0 RECORDS. |
...
search about it. |
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Aaru
Senior Member
Joined: 03 Jul 2007
Posts: 1287
Location: Chennai, India
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In COBOL, you establish the size of a physical record with the BLOCK CONTAINS clause. The performance would be better with larger blocks.
Did a search and found this.
[url]
ibmmainframes.com/about705.html[/url] |
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murmohk1
Senior Member
Joined: 29 Jun 2006
Posts: 1436
Location: Bangalore,India
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Aaru,
| Quote: |
| In COBOL, you establish the size of a physical record with the BLOCK CONTAINS clause. The performance would be better with larger blocks. |
Where did you get this? Is this your personnel view. |
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Aaru
Senior Member
Joined: 03 Jul 2007
Posts: 1287
Location: Chennai, India
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murmohk1
Senior Member
Joined: 29 Jun 2006
Posts: 1436
Location: Bangalore,India
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Aaru,
Did you read this?
| Quote: |
| If you set the block size explicitly in the BLOCK CONTAINS clause, it must not be greater than the maximum block size for the device. The block size set for a format-F file must be an integral multiple of the record length. |
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We recommend that to maximize performance, you not explicitly set the block size for a blocked file in your COBOL source program. For new blocked data sets, it is simpler to allow z/OS to supply a system-determined block size. To use this feature, follow these guidelines:
Code BLOCK CONTAINS 0 in your source program.
Do not code RECORD CONTAINS 0 in your source program.
Do not code a BLKSIZE value in the JCL DD statement.
on the device at run time. If you fix the block size, assuming the |
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